1. Field of the Invention
The present invention relates to management of initialization operations in multiprocessor computer systems. Specifically, the invention relates to a method and apparatus to automatically control the determination of which processor in the system Will boot the system. If the boot processor fails, control automatically shifts to an alternate processor. Additionally, the present invention involves a system wherein each central processing unit includes a corresponding copy of its own boot code. The boot code is transferred to memory for execution by the corresponding processor to carry out initialization operations.
2. Description of the Related Art
The processing requirements of multi-user computer systems for personal and business needs continuously become more demanding. For instance, more complex application programs for use with local area networks are continuously being developed. Moreover, many multi-user systems provide access to more than one operating environment, such as UNIX and DOS, on the same system.
In general, the computers servicing these needs are single processor systems conforming to conventional architectures using a standard input/output I/O bus such as the Extended Industry Standard Architecture (EISA). New and more powerful systems constantly emerge. However, upgrading an old system generally requires investing in substantial hardware modifications or buying a new system.
One solution to the constantly changing power of microprocessors controlling a system is the CUPID architecture designed by AST Research Inc. In the CUPID architecture, the microprocessor based central processing unit (CPU) is not permanently attached to the backplane bus, but is a removable circuit board running at its own speed, asynchronous with the backplane bus operations. Thus, when more power from the microprocessor is desired, a faster CPU can replace the existing CPU.
However, as processing power demands increase, application software and operating systems performance would benefit from an architecture similar to the CUPID architecture, but which has multiprocessor capabilities to provide parallel processing, and to service high numbers of simultaneous users while still retaining high batch performance.
A number of problems hamper the development of such a multiprocessor architecture, such as, determining which processor boots the system, and, if one processor fails to boot the system, enabling another alternate processor to take over boot operations. Moreover, if after one processor boots the system (by executing instructions out of a read-only-memory (ROM)), but another processor utilizes a different instruction set than the boot processor installed in the system, then this other processor will require access to a different boot ROM.